Bucket loader control system

ABSTRACT

A material handling bucket loader with hydraulic boom lifting and bucket curling has an automatic control for bucket curling during the loading operation to assure filling of the bucket. The pressure developed in the boom lift system is utilized to open a normally closed curl valve when the load on the boom reaches a predetermined value which is manually adjustable. Manual override of the automatic curl valve is achieved by sensing the flow which occurs when the manual curl valve is operated and by shifting a shuttle valve in response to such flow.

United States Patent Hallman et al.

[54] BUCKET LOADER CONTROL SYSTEM [72] Inventors: Russell H. Hallman, Royal Oak; John B. Keir, Birmingham; Lawrence J. Patritto, Madison Heights, all of Mich.

[73] Assignee: Sperry Rand Corporation, Troy, Mich. [22] Filed: June 12, 1970 [21] Appl. No.: 45,741

[52] US. Cl ..214/762 51 int. Cl. ..B66t 9/00 [58] Field otSearch ..2l4/l38, 762, 771

[56] References Cited UNITED STATES PATENTS 3,494,495 2/1970 Alderman et al. ..214/762 [4 1 Mar. 21, 1972 Primary ExaminerGerald M. Forlenza Assistant Examiner-John Mannix AttorneyVan Meter and George [57] ABSTRACT A material handling bucket loader with hydraulic boom lifting and bucket curling has an automatic control for bucket curling during the loading operation to assure filling of the bucket. The pressure developed in the boom lift system is utilized to open a normally closed curl valve when the load on the boom reaches a predetermined value which is manually adjustable. Manual override of the automatic curl valve is achieved by sensing the flow which occurs when the manual curl valve is operated and by shifting a shuttle valve in response to such flow.

3 Claims, 4 Drawing Figures PAIENTEUMARZI 1972 3,650,425

sum 1 BF 2 INVENTORS Russell H. Hal/man, Jhn 6 ifez'n wrencelpafrifio m [.72 7 za I i PAIENTEDMAR21 I972 3,55 5

SHEET 2 OF 2 O BUCKET O CONTROLS AUTQMAT l C CUR L OFF ON HEAVY LIGHT LOAD LOAD IF BUCK 0E5 NOT CURL ROTATETO O LIGHTER LOAD 9 K I NVENTORS e11 Hflallman,

ATTORN BUCKET LOADER CONTROL SYSTEM The widely used from end loader for picking up bulk material from piles or from banks presents a disadvantage in that inherently the operator is unable to see the bulk material going into the bucket. Loading is accomplished by driving the vehicle with the bucket facing the material and while crowding the pile or bank simultaneously curling the bucket upwardly and lifting the boom which carriesthe bucket. If the bucket is curled too fast in relation to the lifting operation an insufficient full is obtained, and if it is curled too slowly, the operating time cycle is delayed by the amount of time wasted in crowding a filled bucket against the pile or bank.

The object of the present invention is to provide an automatic bucket curling system which will curl the bucket simultaneously with the lifting of the boom in such a manner that the bucket will automatically start to curl when a predetermined but adjustable force is required to lift the boom.

The invention consists in a hydraulic control system for a bucket loader having a lift-lower valve with a cylinder controlled thereby to lift the bucket, and a curl-dump valve with a cylinder controlled thereby to curl or dump the bucket with the provision therein of an automatic, normally closed, curl valve connected in parallel with the curl-dump valve together with a means which form a pressure responsive actuator for the automatic curl valve and a connection from the lift-lower valve to that actuator for causing the bucket to curl automati cally when the load to be lifted reaches a predetermined amount.

IN THE DRAWINGS FIG. 1 is a cross sectional view of an automatic curl valve incorporated in a preferred form of the present invention.

FIG. 2 is a cross sectional view of a selector valve also incorporated in a preferred form of the present invention.

FIG. 3 is a front view of the selector valve ofFlG. 2.

FIG. 4 is a schematic circuit drawing showing a preferred form of the present invention.

The bucket loader or tractor-shovel illustrated in FIG. 4 has the conventional front end bucket 12 mounted on a boom 14. The conventional hydraulic means for operating the boom and bucket are indicated diagrammatically at the lift-lower cylinder 16 which is manually controlled through lines 18 and 20 by a lift-lower valve 22 with an anti-drop check valve 24 which receives pressure fluid from a pump 26 through the supply line 28 which is monitored by an overload relief valve 30. The bucket 12 has the usual hydraulic operating system comprising the curl-dump cylinder 32 which is manually controlled through lines 34 and 36 by a curl-dump valve 38 having the anti-drop check valve 40 supplied from the line 28. The line 28 extends in series through valves 38 and 22 to an unloading return line 42 going back to the reservoir 44 from which the pump 26 withdraws hydraulic fluid and to which the valves 22 and 38 are connected by return lines 46 and 48.

To these conventional elements of the hydraulic operating system, the present invention adds the automatic curl valve indicated by the dot-dash rectangle 50 and the selector valve indicated by the dot-dash rectangle 52 together with the appropriate connecting lines to the remainder of the system. The automatic curl valve 50 is a normally closed four-way valve which is connected in parallel with curl-dump valve 38 to the cylinder 32 by the lines 5456. has an anti-drop check valve 58, a supply line 60 connected to the supply line 28 and a return line 62 going to the sump 44. Valve 50 may be opened against its bias spring 64 by a contro pressure delivered through a line 66.

The valve 50 is illustrated in detail in FIG. 1 where the body 68 has a main bore 70 receiving a sliding spool 72. Four passages in the body 68 lead to the bore 70 and carry the numbers 54, 56, 60 and 62, they being extensions of the lines cor respondingly indicated in FIG. 4. The bore 70 is closed at its ends by bushings 74 and 76 which form the terminals of lines 66 and 78 respectively. Line 78 leads to the lowering end of the cylinder 16 via line 20. Spool 72 has a through passage 80 which is in communication via a hole 82 with the return line 62 and also communicates with both ends of the bore 70 via restriction plugs 84 and 86.

FIG. 1 shows the valve 50 in its normally closed position with the spool 72 urged tothe left by the biasing spring 64. The admission of pressure fluid through the line 66 at the left end in sufficient volumeto feed the restrictor 84 and in addition overcome the spring bias shifts the spool 72 to the right. This normally happens only during the boom lifting phase as will later be described. However, should it occur at other times when opening of the valve 50 would not be desirable, pressure may be admitted through connection 78 to return spool 72 to its left-hand closed position.

The selector valve 52 is illustrated in FIGS. 2 and 3 wherein the body 88 contains three bores 90, 92 and 94 which are connected by a staggered passage 96 closed at its ends by ball plugs 98. The left ends of the bores 90, 92 and 94 are provided with connections to lines 100, 102 and 104 respectively, while the right end of bore 92 has a line connection 106 leading from the side of the body 88. Bore contains a spring loaded poppet 108 which may be manually opened or closed by means of a threaded knob 110 and lift pin 112. Bore 92 contairis a shuttle valve 114 spring biased to the right. When pressure is admitted through line 106, shuttle valve 114 will shift to the left closing the staggered passage 96. Bore 94 contains a spring loaded pressure responsive relief valve 116. Its pressure setting may be varied by means of a threaded knob 118 which adjusts the position of the tubular valve seat 120 and thus varies the compression of the spring 122.

Referring to FIG. 4, the line which is the inlet line to the selector valve 52 leads from the downstream side of the anti drop check valve 24 in the lift-lower valve 22. Line 102 leads from the downstream side of the anti-drop check valve 40 in the curl-dump valve 38. Line 104, which is the output line from the selector valve 52, connects with line 66 of the automatic curl valve 50. Line 106 connects at the upstream side of check valve 40. A restricted shunt 124, not shown in'FIG. 2, extends between lines 102 and 106.

In operation, the driver of the vehicle positions the boom and bucket as shown in FIG. 4 and crowds the same into the pile or bank from which material is to be loaded. As the crowding slows down or ceases completely, valve 22 is operated to lift the boom. The weight of the material in the bucket develops pressure in the line 18 which is transmitted through line 100 to the selector valve 52. With knob turned to the on position and valve 108 open, and with valve 38 in neutral position, this pressure acts on relief valve 116. Depending upon the adjustment of valve 116 and the density of the material being loaded, this pressure may open valve 116 and be transmitted through lines 104 and 66 to the left end of valve-50 in FIG. 1, to shift the spool 72 to the right. With the proper setting of the knob 118, which is readily determined by trial, the opening of valve 50 actuates the cylinder 32 in a direction to curl the bucket and as lifting and crowding continues, the bucket is filled for transport .and dump.

Dumping may take place in the usual manner by actuation of valve 38. The bucket may be also curled under manual control at any time during the lift-load cycle by merely actuating the manual valve 38. The flow which occurs through anti-drop check valve 40 creates a small pressure drop and this pressure drop is sensed through the lines 102 and 106 at the opposite ends of the shuttle valve 114. This valve may be located either between the valves 108 and 116 as shown in FIG. 2, or beyond the valve 116 as shown in FIG. 4, and whenever it is actuated the passage between the inlet and outlet of selector valve 52 is closed. If at that time the automatic curl valve 50 is open, then this closure of shuttle valve 114 permits automatic curl valve 50 also to close. Thus, the operator has. the continuing ability to override the automatic curl function at will and by the normal means and manner of exercising control of the bucket.

We claim:

1. ha hydraulic control system for a bucket loader having a lift-lower valve with a cylinder controlled thereby to lift and operated.

2. A system as defined in claim 1 wherein the last named means includes a shuttle valve responsive to flow to the bucket cylinder through the curl-dump valve.

3. A system as defined in claim 2 in which the curl-dump valve includes a check valve for preventing back flow from the bucket cylinder and the shuttle valve is connected to respond to the pressure drop across the check valve.

I i t 

1. In a hydraulic control system for a bucket loader having a lift-lower valve with a cylinder controlled thereby to lift and lower the bucket, and a curl-dump valve with a cylinder controlled thereby to curl or dump the bucket, the improvement comprising an automatic normally closed curl valve connected in parallel with the curl-dump valve, means forming a pressure responsive actuator for the automatic curl valve, a connection from the lift-lower valve to that actuator for causing the bucket to curl automatically when the load to be lifted reaches the predetermined amount and means for disabling the automatic curl valve whenever the curl-dump valve is operated.
 2. A system as defined in claim 1 wherein the last named means includes a shuttle valve responsive to flow to the bucket cylinder through the curl-dump valve.
 3. A system as defined in claim 2 in which the curl-dump valve includes a check valve for preventing back flow from the bucket cylinder and the shuttle valve is connected to respond to the pressure drop across the check valve. 